docstr: >>> builder = RequestBuilder(key="", language="", filter_level=1)
  >>> audio_data = AudioData(b"", 16_000, 1)
  >>> builder.build_headers(audio_data)
  {'Content-Type': 'audio/x-flac; rate=16000'}
docstr_tok: [">",">",">","builder","=","RequestBuilder","(","key=","''","''",",","language=","''","''",",","filter_level=1",")",">",">",">","audio_data","=","AudioData","(","b","''","''",",","16_000",",","1",")",">",">",">","builder.build_headers","(","audio_data",")","{","'Content-Type","'",":","'audio\/x-flac",";","rate=16000","'","}"]
code: def build_headers(self, audio_data: AudioData) -> RequestHeaders:
      """
      >>> builder = RequestBuilder(key="", language="", filter_level=1)
      >>> audio_data = AudioData(b"", 16_000, 1)
      >>> builder.build_headers(audio_data)
      {'Content-Type': 'audio/x-flac; rate=16000'}
      """
      rate = audio_data.sample_rate
      headers = {"Content-Type": f"audio/x-flac; rate={rate}"}
      return headers
  
imports: from __future__ import annotations
  import json
  from typing import Dict, Literal, TypedDict
  from urllib.error import HTTPError, URLError
  from urllib.parse import urlencode
  from urllib.request import Request, urlopen
  from typing_extensions import NotRequired
  from speech_recognition.audio import AudioData
  from speech_recognition.exceptions import RequestError, UnknownValueError
label_desc: Use image node_id 4 for calling the RequestBuilder obj's underlying member method code with example usage: obj.build_headers(audio_data) and returns: headers